Both xine and mplayer (from livna and greysector repos respectively) act
like they cannot read the dvd fast enough. Xine plays for about 10
seconds and then freezes for a a second or two, plays some more and then
freezes again. Meanwhile the disk led is dark with minimal activity. The
same thing happens with a mounted DVD in the DVD-ROM drive. So it is not
my disk. Mplayer complains that "Your system is too SLOW to play this!"

It is a 800Mhz athlon with 256MB memory and a nvidia tnt2 AGP using the
nv driver. Although it is older machine, this system was great at
playing DVDs up until a couple of weeks ago. So I suspect a yum update
might have done something. Before this, I have been playing DVDs on it
happily for a couple of years from RH9, to FC4 and now FC5.